The present invention relates to a method and system for transmission of confidential data. The present invention is related to the invention to which commonly-assigned copending application Ser. No. 200,785, filed Oct. 27, 1980, by Robert J. L. Herve, and entitled "SYSTEM AND PROCESS FOR IDENTIFICATION OF PERSONS REQUESTING ACCESS TO PARTICULAR FACILITIES" is directed, the entire disclosure of which is hereby expressly incorporated by reference.
More particularly, the invention relates to systems in which data are transmitted in the form of messages represented in a binary code, as well as in other forms. These messages are coded by means of a coding key upon transmission, and then decoded for restoration to their original clear form upon being received. These systems have at least two disadvantages. The first is the mathematical function enabling decoding of the coded message must be strictly the inverse of the function enabling the message to be encoded. The safety of these systems resides mainly in the fact that the functions applied are complex.
The second disadvantage is the credibility of these systems is assured only if the keys may be easily altered in the course of time, which implies organizing confidential message transmission services for dispatching the keys to the users of the transmission system.